Double-blind trial of promegestone (R 5020) and lynestrenol in the treatment of benign breast disease.

One hundred thirty-two women between the ages of 19 and 50, with various forms of benign breast diseases received 1 mg promegestone, or 0.5 mg promegestone, or 10 mg lynestrenol daily (double-blind), for 15 days per cycle, during three cycles. The groups were identical before treatment, with the exception of a longer history of mastodynia and mastopathies in the 1 mg promegestone group than in the lynestrenol group (P = 0.04) and a greater proportion of mastosis zones in the lynestrenol group as compared to the 0.500 mg promegestone group (P = 0.05). The effectiveness of lynestrenol both in terms of symptomatology (evaluated as good or excellent in 66.6% of the cases) and of clinical observations (evaluated as good or excellent in 59% of the cases) is not significantly different statistically from that of promegestone at 1 mg, whose effectiveness on symptomatology was good or excellent in 65.9% and 57.1% of the cases, respectively, or from that of promegestone at 0.5 mg/day (with 65% and 51.3% effectiveness, respectively). Clinical tolerance was rated good or excellent for 73.9% of the women on 1 mg promegestone and for 59.5% of the women on 0.500 mg promegestone, compared to 66.7% of the women on lynestrenol. No statistically significant difference was observed, neither between lynestrenol and promegestone 1 mg nor between lynestrenol and promegestone 0.5 mg. This study shows a clear improvement in functional and physical signs in patients treated with promegestone. Promegestone's efficacy is close to that of lynestrenol, a nonsteroidal progestin.2+ off